The proposed program of projects is comprised of several investigations having overlapping interests and many common experimental approaches. Projects have similar objectives in their focus on the general area of mental retardation and other neurologic diseases, seeking improved diagnostic procedures, new therapeutic measures, and elucidation of specific biochemical defects. The investigations encompass broadly the disciplines of biochemistry and genetics with specific projects ranging from basic to clinical in nature. The several projects involve several areas of metabolism including carbohydrates, lipids, pyrroles, mucopolysaccharides, amino-acids, and trace metals. Specific disease entities being investigated include homocystinuria, congenita lactic acidosis, Tay-Sachs disease, Menkes disease, acute intermittent porphyria, lead intoxication, Krabbe's disease, metachromatic leukodystrophy, and Fabry's syndrome. BIBLIOGRAPHIC REFERENCE: Giddens, W.E., Jr., Labbe, R.F., Swango, L.J., Padgett, G.A.: Feline congenital erythropoietic porphyria associated with severe anemia and renal disease. Am J. Pathol 80:367-380, Sept. 1975.